Gas lift apparatus



April 14, 1953 R. o. WALTON GAS LIFT APPARATUS Filed Aug. l0, 1946FIC-3.3

ROBERT O. WALTON INVEN TOR Y ATTORNEY Patented Apr. 14, 1953 UNITEDSTATES PATENT (')FFICEv GAS LIFT APPARATUS Robert O. Walton, CorpusChristi, Tex. Application August 10, 1946, Serial No. 689,687

10 Claims. l

This invention relates to gas lift apparatus employed in deep wells forproduction purposes and is more particularly directed to injectionvalves commonly employed with such apparatus.

Two general types of valves are most commonly employed in suchapparatus. In one, the valve is constructed with a pre-set pressureresponsive means arranged to respond directly to some predeterminedpressure differential between the pressure of the injection gas and thatof the fluid column to be moved thereby. In the other, although theactual transfer of gas from a lifting gas reservoir through theinjection valve to the iiuid column to be moved is responsive to thedifferential in their respective pressures, movement of the valvemechanism itself is controlled by mechanism within the valve arranged tooperate upon the pop-valve principle, that is, one which includes amechanism responsive to a predetermined difference in pressure betweenthat of the injection gas and the opposing pressure of a movable elementsuch as a spring o-r pressurefluid loaded diaphragm, bellows or pistonwhich is pre-set at a fixed pressure.

All such prior art devices are subject to a serious operating limitationin that the pre-setting means must be set before the valve is run in thewell and such pre-setting is controlled by the particular pressureconditions which it is anticipated will be used in the well. Thus, thevalve, having once been set, if the relative pressure levels of theavailable source of lifting gas and of the iiuid column to be liftedchange substantially from the original levels, the valves must bewithdrawn from the Well and reset for operation in accordance with thenew pressure levels. Since, in many cases, the source of supply of thelifting gas is not constant-I or uniform, either as to pressure orvolume, or the pressure in the source reservoir of the liuid to be movedis like- Wise subject to change, this often requires repeated Withdrawalof the tubing string, to which the valves are normally attached, andmanual resetting of the valves for operation at the changing pressurelevels with consequent considerable expense and loss of productionJtime. Furthermore, in the prior art devices which employ a pressureuidloaded moving member, the pressure fluid employed is not the injectionfluid but is gas or liquid which is enclosed within a hermeticallysealed chamber.

disadvantage previously mentionedl of requiring re-setting for changingpressure conditions under which they are operated, also are subject tothe further disadvantage that the hermetically sealed chamber may leakand thereby undesirably Such devices in addition to the i 2 change thesetting of the valve. Moreover, popvalve type units generally require alarge pressure diierential across the bellows or diaphragm which tendsto cause rupturing of such members.

It is a principal object of this invention, therefore, to provide agas-lift apparatus employing injection valves which may be reset toaccommodate changing pressure levels by pressure and volume adjustmentsat the top of the Well, Without requiring removal of the valves from thewell.

Another important object of this invention is to provide an improvedform of injection valve which is operable at an original pre-setdifferential pressure independent of the pressure level of the actuatinggas, or of the fluid to be lifted thereby.

Another object of this invention is the provision of an improved form ofinjection valve which is adapted to operate in response to apredetermined differential pressure of the actuating gas across a valveoperating member, opposed surfaces of Which are exposed to the pressureof the same actuating medium.

A further object of this invention is to provide an injection valve inwhich the operating member is subjected to the pressure of theyactuating gas acting upon opposed surfaces thereof, Wherein means areprovided for establishing a predetermined difference in pressure of theactuating gas on the opposed surfaces.

A more specific object of this invention is the provision of aninjection valve having a valve member connected to a flexiblevalve-moving memberlhaving opposed surfaces exposed to the sameactuating gas, one of the surfaces being enclosed within a chamber,which is provided with valved passageways communicating with the sourceof actuating gas, whereby a differential pressure of the actuating gasmay be maintained acrossy the flexible member.

Still another object is the provision of an injection v-alve which isoperable at different pressure levels merely by controlling the pressureat the source of the actuating gas.

A further important ob-ject is the provision of injection valves which,when installed serially along a column of fluid to be moved thereby, maybe operated at successively higher operating pressures in descendingorder `along the'column, to thereby utilize to a maximum degree theenergy available in the injection gas.

Other and more specific objects and advantages of this invention willbecome apparent from the following detailed description When read inconjunction With the accompanyingy drawings which illustrate usefulembodiments of this invention.

In the drawings:

Fig. 1 is a semi-diagrammatic longitudinal section through a wellinstallation illustrating one use of the valve structure of thisinvention;

Fig. 2 is an enlarged vertical section through a valve unit constructedin accordance with one embodiment of the present invention; and

Fig, 3' is a view similar to Fig. 2 through -a valve constructed inaccordance with another embodi ment of the present invention.

Referring to the drawings, and in particular to Fig. 1, there is shown aportion of a well casing I0 of any conventional type through which thereextends a tubing I I of smaller diameter than the the casing and throughwhich oil or other fluids are adapted to ow from the well to the surfaceof the ground, whence such fluids are discharged through a pipe I2fitted with a valve I3 to suitable separators or storage devices (notshown).

The top of the casing surrounding the tubing II is closed by aconventional casing head Ill near the upper end of which, incommunication with the annular space between the casing and tubing(hereinafter called the annu1us), is a pipe I5 tted with a control valveI 6. Located along tubing II in the annulus and suitably connected totubing ll at suitable intervals are a plurality of now valves, indicatedgenerally by the numerals I'l, of the type to which this inventionrelates.

The number vof such flow valves will vary with the type of well, itsdepth and other conditions pertaining to the particular well. Valves IIare connected, as is generally conventional, to suitable tubing nippleswhich are connected into the tubing string by means of collars lla. Thetubing II may be packed-01T from the casing by a conventional packingmember, indicated in dotted outlines by the letter P, or the operationto be hereinafter described may be conducted withf out the use of such apacker, both arrangements being conventional in the art to which thisinvention relates.

Fig. 2 illustrates more particularly the detailed construction of valvesI'I. A passageway I8 extends through the wall of tubing I I and isformed by a threaded tubular seat bushing I9 which is screwed through aboss 2G arranged concentrically about a suitabl-e opening 2l in the wallof the tubing. The outer end of seat bushing I9 is provided with acircular seat 22 adapted for the seating of a conical valve member 23,having a generally cylindrical extension 24, which extends intopassageway I8 and serves as a guide for the seating of valve member 23.Valve member 23 is enclosed within a dome-shaped housing comprising agenerally tubular section 25, one end of which is welded or otherwiseconnected to the wall of tubing I I to form a leak-proof connectiontherewith. The outer end of section 25 is provided with a generallydome-shaped cover 26, which is fastened to the outer end of section 25in any suitable or conventional manner. A diskshaped flexible diaphragm2'I has its edge peripherally tightly clamped between the end of section25 and cover 26 of the valve housing and forms a leak-proof partitionbetween the interior of section 25 and a chamber 28 formed by the areabetween the outside of diaphragm 2'I and the inner wall of cover 26. Therelative areas of seat 22 and diaphragm 21 will preferably be soselected that when maximum casing pressures used for the valve operationare attained, thereby creating maximum pressure diiierentials acrossseat across diaphragm 2'I, neces- 22, the differential sary to raisevalve member 23 from seat 22 will not exceed the setting of inlet valve33. The outer end of valve member 23 is firmly connected to the centerof diaphragm 21 by means of a stud 29 which extends through a dishedreinforcing plate 30, arranged to cover the central portion of the outerface of diaphragm 21, and into a boss 3I on the outer end of valvemember 23. The opposite face of the wall of cover 26 is suitablycontoured to comp-lement the contours of reinforcing plate 39. This faceof cover 26 acts as a stop to limit the extent of the outward movementof diaphragm 27. The size and form of diaphragm 21 are so chosen withrelationship to the depth of chamber 28 and the length of travel ofvalve member 23 to avoid undue stretching of the diaphragm in responseto the difference in pressures on the opposite sides thereof, to therebyprevent rupturing thereof during operation.

Cover 2S has a passageway 32 therethrough providing communicationbetween the exterior oi the valve housing and chamber 23 and has mountedtherein a spring-controlled pressure relief valve 33 constructed andarranged to permit passage of nuids in one direction only, namely fromthe exterior of the valve housing into chamber 23.

A second passageway 34 through cover 25 is similarly tted with a springcontrolled pressure relief valve 35, which is 4arranged therein topermit flow of uid only outwardly from chamber 28 to the exterior of thevalve housing. For purposes of this description, valve 33 will bedesignated as the inlet valve and valve 35 as the exhaust valve forchamber 28. Valve 33 will normally be set to maintain some suitablepressure dinerential between the exterior of the valve housing andchamber 28. For example, valve 33 may conveniently be set to maintain -apressure diiferential of fifty pounds per square inch gauge betweenchamber 28 and the exterior of the housing. Ex.m haust valve 35 willnormally be set to maintain a, lower differential pressure, generally ofthe order of about ten pounds per square inch gauge. Connected to cover2E is a pressure expansion reservoir 35, which communicates with theinterior of chamber 28 through a passageway 31. Extending through thewall of section 25 of the valve housing, and communicating with theinterior thereof, is a, generally cylindrical inlet tube 38, the outerend of which is closed and provided with a plurality of ports 39. Thecombined area of all the ports 3S is made greater than the area ofpassagew-ay I8. At an intermediate point in inlet, tube 38, betweenports 39 and the interior of section 25, there is located an annularshoulder 40 which forms a seat for a flapper type check valve 4I, whichis hingedly attached at 42 to the side of inlet tube 38. With thisarrangement, check valve 4I is operable to admit iluid moving from ports39 to the interior of section 25 while preventing movementV of fluid inthe opposite direction.

The valve mechanism described above is employed in the following mannerin iiowing well uid from the well through tubing I I At the beginning ofoperations, tubing i i fitted with a requisite number of valves I'I,will have been run into the well through casing I6 and a static level ofwell uid will normally be present at some point in the casing and tubingabove the level of the producing horizon and below the top of thecasing. The uppermost valve I'I may be positioned in the tubing stringso that it will be just above the static level of the well uid, althoughit may be placed so as to be submerged initially. The inlet and exhaustvalves 33 and 35, respectively, will have been set at the desireddifferential pressures, for examples at fty pounds in the case of inletvalve 33 and ten pounds in the case of exhaust valve 35. A supply ofactuating gas at relatively high pressure will then be admitted throughpipe I5 under the control of valve I6 into the annulus, at greatervolumes than can be passed by flow valve I1 until the desired operatingpressure has been reached within the annulus. Assuming the uppermostvalve I1 to be above the static level of the well fluid in the casingand tubing, the actuating gas will enter ports 39 in inlet tubing 38lifting check valve 4I and passing into the interior of section 25 ofthe valve. At the same time the actuating gas, since it surrounds valveI1, will also ilow through passageway 32 into chamber 23, since thepressure of the actuating gas will normally be substantially in excessof fifty pounds per square inch, the setting of inlet valve 33. As aresult, both faces of diaphragm 21 will be exposed to the pressure ofthe same actuating gas, but since a differential pressure of fiftypounds exists across the diaphragm, the pressure within chamber 28 willbe fifty pounds lower than the pressure within the interior of section25 of valve housing and in the surrounding annulus. This pressuredifferential will force diaphragm 21 to f3 move inwardly of chamber 28toward cover 23, moving valve member 23 in the corresponding directionand opening passageway IS to admit actuating gas into the interior oftubing I I. The

gas thus admitted will, of course, flow upwardly through the tubing tothe top of the well. This operation will continue until the desiredoperating pressure is reached and the gas supply at the surface isclosed off. This will allow the pressure within the lannulus passagewayI8 into tubing I I to a point below that which was reached due to theexcessive volumes of actuating fluid which were being admitted, untilthe pressure within chamber 28 is slightly greater than the pressure inwill cause valve member 23 to seat on seat 22. When actuating fluid isagain introduced into the annulus through valve 'I 6 the pressure withinthe annulus increases and as the actuating fluid is injected into theannulus normally at a modne erate rate, the pressure increase isrelatively slow, and this will gradually raise the pressure within theannulus to a point above that present within chamber 28 (during theopening and closing of the valves, there is no migration of fluidthrough valves 33 and 35 unless it is desired to change the annulusoperating pressure). As there is a greater differential across the seats22 of the upper valves than there is across the seats 22 of the lowervalves, the lower valves will open first, due to a smaller diierentialacross diaphragm 21 being necessary to raise valve member 23 from seat22 of these valves. This will allow the well liquid to flow from theannulus into tubing II and rise therein above passageway i8 of theuppermost valve before this valve will open. When the pressure withinthe annulus has increased sufficiently above the pressure in chamber 28of the uppermost valve to raise its valve member 23 from seat 22, thengas will be admitted through passageway I8 into tubing Ii and the fluidabove passageway I3 will be lifted to the surface. This lifting will beaccomplished, either by aeration of the iiuid column or by forming slugsof gas in the fluid column which act as gas to be dissipated through theannulus which pistons to drive the segment of liquid above passageway I8toward the top of the well from which it will flow through valve I3 andpipe I2 to suitable separators of storage vessels (not shown), dependingupon whether the gas admitted through pipe I5 and valve IB is admittedby means of conventional intermitting devices or in a continuous mannerby means of a suitable choke arrangement also conventionally used in gaslift operations.

The other valves I1 further down in the string will also be opened bythe combination of the gas pressure exerted against the top of thecolumn of fluid in the annulus and the weight of the column of fluidstanding above each of these valves. However, in the case of the valveswhich are thus initially submerged in liquid, since the pressure of theliquid'surrounding the valves will exceed the fifty-pound setting ofinlet valve 33 when#- ever the head of liquid exceeds this pressure asthe valves are submerged, liquid from the annullus will flow intochamber 28 and when the pressure of the surrounding fluid exceeds thefifty pound dierential maintained by valve 33, the diaphragms 21 ofthese submerged valves will also, as in the case of the uppermost valve,be urged toward cover 26 and open their respective passageways to thetubing. The uid trapped in the chambers 28 of the several submergedvalves will be compressed by the movement of the diaphragms and will beforced through the re` spective passageways 31 into the pressureexpansion reservoirs 36. The latter will normally contain air originallypresent at atmospheric pressure and this will be compressed by theliquid entering reservoirs 36. When the diaphragms 21 are flexed in theopposite direction in closing the valves, the liquid in reservoirs 36will flow back into the respective chambers 28 and the trapped air inreservoirs 35 will expand correspondingly. The initial trapping ofliquid in chambers" 23,v will thus in no way hamper the successfulfunctioning of the valves, and the movement of the valves will remainresponsive to the differential pressure of the actuating gas operatingon opposite faces of diaphragms 21. A

The operation may be begun, if desired, by initially closing valve i3 onthe tubing while the actuating fluid is beingy injected through valve I6into the annulus. This will prevent a wastage of lifting fluid fromescaping through valve I3 tothe surface while necessary pressure isbeing attained 'in the annulus. After the desired pressure is reachedvalve I6 will be lclosed and valve I3 opened. This will allow thepressure on the tubing to be dissipated to the surface receivers, andvalve I1 will pass actuating uid into' the tubing until the pressure inthe annulus has dropped slightly below the pressure in chamber 28, whichwill allow valve member 23 to be moved to its seat 22 by the higherpressure on diaphragm 21.

If the intermitting system of introduction of successive volumes of gasis employed, valve I6 will, of course, be closed as soon as the desiredpressure is attained in the annulus as described above. The applicationof the pressure of the actuating gas through valve I5 will open valvevsuccessive volumes of gas is employed, valve I6 will be left open onlylong enough to pass enough gas into the annulus to open valve member 23and t-o lift the desired column of well fluid to the surface. Thepressure increase on the ani nulus will not be great enough to causeadditional pressure fluid to pass into chamber 28.' When valve IB isclosed the pressure in the annulus will be'dissipated into the tubinguntil the pressure in this area is slightly lower than the pressure inchamber 28. Then valve member 23 will be closed by the action ofdiaphragm 21-the valves being so constructed as to the ratio of areas ofdiaphragm 21 and seat 22, that only a very small pressure differentialacross diaphragm 21 is required to close valve 23. This being 'the case,no pressure will bleed out of chamber 28 in normal operation. Thisprocess of opening Valve l 6 to admit gas to the annulus at a moderaterate to cause the lower valves to open and pass the Well liquid from theannulus into the tubing Il and to then cause the uppermost valve to openand pass lifting gas under the column of fluid in the tubing, followedby closing valve I6 and allowing pressure 4to be dissipated toattainment of the valve closing point, is repeated until enough wellfluid has been removed from the annulus so that the second valve isexposed lto the lifting gas. At this point there will be a smallerdifferential across seat 22 of the second valve than there is across theseat 22 of the uppermost valve. so less pressure increase will berequired to open valve member 23 of the second valve 'than to open theuppermost valve. The second valv-e will start operating exactly as theuppermost valve did and will continue operation until the next lowervalve is reached at which time the third valve will start to functionwith gas injection, this operation being repeated for each successivelylower valve until the bottom valve has been reached by the lifting gas,at which time it will continue to operate vindependently of the othervalves due to the fact that it will have a heavier column of well liquidin the tubing above its passageway i8 and will th-ereby have a smallerdifferential across itsv seat 22 and will, therefore, be opened by alesser pressure increase than the upper valves.

At this point, if an intermitter has been employed to supply actuatinggas in the manner described to unload the tubing, the control of valveI6 may be switched to a continuous operation by employing a conventionalchoke control which will continuously feed in sumcient gas to theannulus to maintain the lowermost valve in an open position, at thedesired operating pressure, so as to continually feed into the tubingsuicient gas to continually aerate the fluid column in the tubing andkeep it flowing to the top of the well. Of course, the intermittentoperation may continue to be employed, if desired, and the typ-e of nalflowing operation will depend largely on the conditions obtaining at theparticular well.

With ya valve of the form above described, it will be seen that openingand closing of the valve will be primarily dependent upon the pressuredierential maintained across diaphragm 21 by means of inlet valve 33,irrespective of the average pressure of the actuating gas. Thus, if itis desired to operate the valves at some higher average operatingpressure than that initially employed, it is only necessary, by suitablemanipulation of the surface controls, to increase the pressure andvolume of the employed actuating gas to attain the desired pressure inthe annulus, whereupon the average operating pressure of the valve willbe correspondingly increased, since inlet valve 33 will continue tofunction to maintain the initially determined pressure differentialacross diaphragm 21.

Similarly, when it is desired that the valves should function at anaverage operating pres,- sure below that originally employed, thepressure in the annulus is allowed to drop to the desired level bysuitable manipulation of the surface controls and exhaust valve 35 willexhaust fluid from chamber 28, always maintaining its pre-setdifferential pressure in the chamber, until the desired pressure levelis reached. Thereafter, when actuating gas is admitted to the annulus,the pressure outside and inside chamber 28 will build up correspondinglyand the preset differential pressure controlled by inlet valve 33 willbe reestablished and the valves will function exactly as previouslydescribed, but at the lower pressure level.

From the foregoing, it will be evident that the opening and closing ofthe valves is strictly a function of increasing and decreasing pressurewithin the annulus and such opening and closing may be effected at anyaverage operating pressure desired. Furthermore, since the valves areall normally constructed to the same specifications, the greater thedifferential pressure across the several seats 22, the greater will bedifference between the'opening and closing pres` sures of the valves inthe series. Thus at any given operating pressure, each valve indescending order will open preferentially relative to the valves aboveit, because with a column of fluid standing in tubing Il, thedifferential pressures across seats 22 will be successively lower foreach valve in descending order in the series. However, if desired, thepressure differential across the diaphragme 21 may be set differentlyfor each valve unit, by suitably varying the settings of inlet valves 33and exhaust valves 35, so that the lowest pressure differential is setfor the uppermost valve in the string in such manner that as thepressure increases in the annulus, the total pressure load created bythe pressure differential across seat 22 will be greater than thepressure load created by the pressure differential across diaphragm 21,This means that once the pressure surrounding the valve unit increasesbeyond the pre-determined setting, valve member 23 cannot be raised fromseat 22 unless there is a low pressure differential across seat 22, thispressure differential across the seat being dependent upon the load ofliquid in the tubing above the valve level. Since the pressuredifferential across the seat of a lower valve isless than that above ahigher valve under a given head in the tubing, then, by increasing thepressure in the yannulus as each valve is uncovered, the successivevalves could be operated at successively higher pressures, the uppervalves being kept closed as the increasing operating pres-y sureproduces pressure differentials across the seats of the higher valveswhich are in excess of the pre-set pressure differentials of thesevalves.

Fig. 3, which illustrates another embodiment in accordance with thisinvention employs a somewhat modi-hed form of valve moving member inplace of diaphragm 21 of the embodiment illustrated in Fig. 2. Asillustrated in Fig. 3, the valve includes a hollow L-shaped chamber 45mounted on the side of tubing I l so that one end of the chamber opensupwardly parallel to the tubing. The other end of the chamber is con-Jnected to the side of the tubing in liquid tight engagement therewithand the wall of the tubing is provided with a passageway 46 furnishingcommunication between the interior of chamber 45, and the interiorl ofthe tubing. A generally tubu. lar housing 41, the lower end of which isprovided with a. threaded extension 48, is screwed into the upwardlyopening end of chamber 45.: Extension i8 is provided with an axialpassageway 49 which provides communication between the interior ofhousing 41 and chamber 45. The lower end of passageway 49 is closed bymeans of a valve member 55 having a stem 5l fitted in a sleeve 52mounted on the bottom of chamber 45. A coil spring 53 is mounted withinsleeve 52 and acts against the end of stem l to normally urge valvemember 5i) in a direction to close the lower; end of passageway 59. Atubular seat bushing 54 is screwed into the upper end of extension 48from within housing 41 and has its bore aligned with passageway 43. Avalve member 55 provided with an upwardly extending stem 55 is arrangedto move axially of housing 4l in opening and closing the passagewaythrough seat 54. The upper end of valve stem 56 is firmly attached tothe lower end of a hollow bellows 51, of generally conventionalconstruction, enclosed within housing 41 and having its upper peripheryconnected in liquid-tight engagement to an annular shoulder 58 arrangedin the upper portion of housing 41. The upper end of housing 41 extendsfor a short distance above the upper end of bellows 53 and is closed byan end plate 59 forming a chamber Si! within the bore of the housingwhich is in communication with the intericr oi" bellows 58. By thearrangement described bellows 58 forms a fleixble liquid-tight partitionin housing 41 separating chamber 5b from the balance of the interior ofthe housing., Cover 59 is provided with a passageway 6l, which providescommunication between the exterior of the housing and chamber 50.Passageway 59 is fitted with a spring loaded pressure relief valve 82and which corresponds in construction and function tc inlet valve 32 ofFig. 2. Passageway 53 is also provided in cover 59 likewise furnishingcommunication between the exterlor of housing 41 and chamber 65 and isfitted with a springloaded pressure relief valve 54, which correspondsin construction and function to exhaust valve 35 of Fig. 2. A pressureexpansion reservoir 65 is mounted on cover 5S and communicates withchamber 55 through a passageway 56 extending through cover 55. A seriesof inlet ports 61 are provided in the wall of housing d1 intermediatebetween extension 4S and shoulder 58 and provides communication betweenthe exterior of the housing and the portion of the interior thereofbelow shoulder 58. The total area of all of the ports 51 is made greaterthan the area of the pas-,- sageway through seat 54.

The embodiment illustrated in Fig. 3 operates in substantially the samemanner as that shown in Fig. 2 and described above. Inlet Valve 52 andexhaust valve 5d are set at predetermined pressures, such as waspreviously described for valves 33 and 35, to maintain a predetermineddifferential pressure in chamber 55. The innen and outer surfaces ofbellows 51 are therefore subject to the difference in pressure of thesame actuating gas just as in the previously described modification,bellows 5l being compressed to lift valve member 55 from seat 513 toopen the valve when the pressure of the actuating gas external-l ly ofthe bellows exceeds the pressure inside the bellows as controlled by thevalves in cover 59. Similarly, when the pressure exterior of the bellowsis less than the pressure within chamber 60 the bellows will be extendedand Valve member 55 moved into the valve closing position. Valve member5D operates in a manner corresponding to check valve 4l of theembodiment of Fig. 2 in that it likewise acts as a check valve when thepressure load in tubing Il exceeds the pressure load at the opposite endof passageway 4S. In all other respects the embodiment illustrated inFig. 3 functions in exactly the same manner as was previously describedin connection with the embodiment illustrated in Fig. 2.

It will be understood that although the above described embodiments areillustrated and described as arranged for the injection of the actuatinggas from the annulus into the tubing, the valve units may, if desired,be positioned within the tubing and operated to direct the flow ofactuating gas from the tubing into the casing for the purpose of liftingiiuid from the annulus rather than from the tubing. This alternativearrangement is entirely conventional in gas lift apparatus of the classto which this invention is applicable.

The pressures at which inlet and exhaust valves 33 and 35 in Fig. 2 and62 and 64 in Fig. 3 may be set may, of course, be varied from thefigures given above merely by way of example. Since, however, the formof valve in accordance with this invention successfully lends itself tothe use of relatively low differential pressures, of the order oi'magnitude mentioned above, across the diaphragm or bellows, as the casemay be, the danger or" rupturing these flexible members is greatlyreduced and the operating life of the valves is thus substantiallyincreased.

It will be understood that various changes and alterations may be madein the embodiments described above without departing from the spirit ofthis invention but within the scope of the ap-1 pended claims.

What I claim and Patent is:

l. A gas injection valve comprising, a valve member adapted to control agas injection passageway, an operating member for moving said valverelative to said passageway, a housing enclosing said operating memberhaving means for exposing opposed surfaces of said operating member tothe pressure of the same actuating gas, and differential pressureoperated valve means connected to said housing on one side of saidoperating member and pre-set to maintain the pressure of said actuatinggas on one side of said operating member within a predetermined rangeabove and below the pressure or' said gas on the opposite side of saidoperating member.

2. A gas injection valve comprising, a valve member adapted to control agas injection passageway, a housing enclosing said valve member, anexible member mounted in said housing to form a Huid-tight partitiontherein, said valve member being connected to Said flexible member andmovable thereby relative to said passageway, ports in said housing foradmitting actuating gas therein on opposite sides or said flexiblemember, and differential pressure operated valve means connected to theports on one side of said flexible member and pre-set to maintain thepressure of said gas thereon within a predetermined range above andbelow the pressure on the opposite side of said flexible member.

`Si. A gas injection valve comprising, a valve member adapted to controla gas injection passageway, a housing enclosing said valve member, aflexible member mounted in said housing to form a fluid-tight partitiontherein, said valve member being connected to said flexible member andmovable thereby relative to said passageway,

desire to secure by Letters ports in said housing for admittingactuating gas therein on opposite sides of said partition, and pressureregulating means cooperating with the ports on one side of saidpartition to maintain thereon a pressure of said actuating gas within apredetermined range above and below the presure on the opposite side ofsaid partition, said pressure regulating means including a pair ofpressure relief valves set at different pressures, .the one set at thehigher pressure being arranged to direct flow of gas inwardly of saidhousing and the other to exhaust gas from said housing.

4. A gas injection valve comprising, a valve member adapted to control agas injection passageway, a housing enclosing said valve member, aiiexible member mounted in said housing to form a fluid-tight partitiontherein, said valve member being connected to said flexible member andmovable thereby relative to said passageway, ports in said housing foradmitting actuating gas therein on opposite sides of said partition,pressure regulating means cooperating with the ports on one side of saidpartition to maintain thereon a pressure of said actuating gas Within apredetermined range above and below the pressure on the opposite side ofsaid partition, and an expansion chamber communicating with said housingon the side of said partition controlled by said pressure regulatingmeans.

5. A gas injection valve comprising, a valve member adapted to control agas injection passageway, a housing enclosing said valve member, aexible member mounted in said housing to form a fluid tight partitiontherein, said valve member being connected to said iiexible member `andmovable thereby relative to said passageway, ports in said housing foradmitting actuating gas therein on opposite sides of said partition,check valve means connected to Ithe ports on one side of said partitionto direct iiow of iluid inwardly only of said housing, and differentialpressure operated valve means connected to the ports on the oppositeside of said partition and pre-set to maintain thereon a pressure ofsaid actuating gas within a predetermined range above and below thepressure on said one side of said partition.

6. A gas lift system for wells, comprising, in combination with a casinghaving a tubing therein provided with a plurality of gas passagewaysestablishing communication at vertically spaced points between thecasing and tubing and means at the top of .the well for supplyinglifting gas to said passageways under controlled conditions of volumeand pressure, valve members controlling each of said passageways,operating members connected to each of said valve members, each of saidoperating members having opposed surfaces exposed to the pressure ofsaid lifting gas, a housing enclosing each of said operating members,and differential pressure operated valve means connected to each of saidhousings and pre-set to maintain the pressure of said gas in saidhousings on one side of each of said operating members within apredetermined range above and below the pressure of said gas on theopposite side of each of said operating members, said range being thesame for each of said valve members.

'7. A gas lift system for Wells, comprising, in combination with acasing having a tubing therein provided with a plurality of gaspassageways establishing communication at vertically spaced pointsbetween the casing and tubing and means at the top of the well forsupplying lifting gas to said passageways under controlled conditions ofvolume and pressure, valve members controlling each of said passageways,operating members connected. to each of said valve members havingopposed surfaces exposed to the pressure of said lifting gas, a housingenclosing each of said 0D- erating members, and differential pressureoperated valve means connected to each of said housings and pre-set tomaintain the pressure of said gas in said housings on one side of eachof said operating members within a predetermined range above and belowthe pressure of said gas on the opposite side of each of said operatingmembers, said range being of increasing magnitude for said valve membersin descending order along said tubing.

8. A gas lift system for wells comprising in combination with a casinghaving a tubing therein provided with a plurality of gas passagewaysestablishing communication at vertically spaced points between thecasing and tubing and means at the top of the well for supplying liftinggas to said passageway under controlled conditions of volume andpressure, valve members controlling each of said passageways, operatingmembers connected to each of said valve members having opposed surfacesexposed to the pressure of said lifting gas, a housing enclosing each ofsaid operating members, and differential pressure operated valve meansconnected to each of said housings and pre-set to maintain the pressureof said gas in said housings on one side of each of said operatingmembers within a pre-determined range above and below the pressure ofsaid gas on the opposite side of each of said operating members.

9. A well flowing device of the character described comprising, ahousing having a passage therein, a valve in said passage, a chamberincluding pressure responsive means movable to actuate said valve underthe influence of ambient pressures exteriorly of the housing, and aloaded inlet valve to said chamber for admission of a charging pressureto the chamber from the ambient pressure exteriorly of the housing, saidinlet valve being loaded to charge said chamber at a pressure less thanthe maximum value of the ambient pressure by a predetermined amount.

l0. A well flowing device of the class described comprising, a valvehousing having a passage therein, a valve in said passage, distensiblemeans operatively connected to said valve to move the valve to and fromclosed position, a volume chamber communicating with said means, andmeans responsive to ambient pressure for maintaining within apredetermined range the differential in pressure between the interiorand the exterior of the chamber, said last mentioned means includinginwardly and outwardly opening check valves operable to admit andexhaust pressure fluid to and from the volume chamber when differentialpressures develop in excess of predetermined maxima.

ROBERT O. WALTON.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,952,581 Boynton 1 Mar. 27, 1934 2,212,709 Grove Aug. 27,1940 2,250,464 Boynton s July 29, 1941 2,271,031 Parker Jan. 27, 19422,339,487 King Jan. 18, 1944 2,342,301 Peters Feb. 22, 1944 2,375,411Grant May 8, 1945 2,377,981 Taylor June l2, 1945 2,385,316 Walton Sept.18, 1945

